Most gifted children in the United States spend the majority of their school time in regular classroom settings, grouped with age peers who have a wide range of academic achievement and potential. This expansive range of needs in every classroom underscores the importance of assessing all students appropriately and providing differentiated curriculum and instruction that will promote their learning. Differentiation includes: (1) the design and/or selection of curriculum; (2) the selection and use of instructional practices, including grouping strategies, varied resources, and variations to the pacing of instruction; and (3) the assessment of learning, all of which rely on assessment evidence demonstrating learner differences. The National Association for Gifted Children maintains that at a minimum, schools must ensure that gifted children are provided with appropriately differentiated curriculum and instruction to support continuous growth in the regular classroom setting. However, differentiation must be viewed as an approach that is necessary but not sufficient to comprehensive service delivery for gifted learners (Hertberg-Davis, 2009). Differentiation within heterogeneous classrooms should not replace more intensive services for gifted learners that may be provided through resource support, full-class grouping models, or other approaches.